1. The Field of the Invention
The present invention is directed generally to a ramp system. More specifically, the present invention is directed to a ramp system leading from a flexible cableway to a rigid rail to enable the movement of persons or goods to and from the cableway by means of a self-propelled trolley.
2. Background Art
U.S. Pat. No. 2,198,536 to Johansen et al. teaches a moveable rail configured to smooth the transition between a flexible cableway and a rigid rail. The ramp, however, was of the same hardness as the cableway and therefore repeated trolley passage on the ramp rubbed the cable leading to abrasion of the cable. Also, the ramp lacked a surface modification that would allow a trolley to climb a steeper angle.
This was not a problem in the prior art since the cableway was a high tension cableway where the approach angle tended to be small, i.e., less than 3 degrees. However, where there is a cableway having low tension, there would be larger sag which in turn would result in a greater approach angle for any given load. This approach angle is greatest near to the connection with the rail support. An additional complication with a low tension cableway is that a self-propelled trolley moves due to contact of the drive wheel with the cable. When the ramp is steep and/or wet, the drive wheel may lose traction and the trolley will not climb the grade.
Elevated rail systems of one or more rails are expensive to install, since the catenary nature of suspended cables makes trolley movement along them difficult due to the rising and falling of the cableway between supports. In order to overcome this, one can employ a high tension cable way as used in banana trams or an overhead support cable that holds the rail system and its cable in about a linear or contra-catenary path. In both cases, the line support cable causes a supported cable to be more linear and allows smooth transitions from spans to supports. A problem with the high tension cableway is that it needs exponentially larger numbers of supports as the load increases.
Thus, there arises a need for a mechanism which enables the use of low tension cable with self-propelled trolleys.